Statut  Confirmé 
Série  IPNTHEO 
Domaines  nuclth 
Date  Jeudi 26 Juillet 2018 
Heure  11:30 
Institut  IPN 
Salle  Bâtiment 100, Salle A015 
Nom de l'orateur  Dupuis 
Prenom de l'orateur  Marc 
Addresse email de l'orateur  
Institution de l'orateur  CEA, DAM, DIF 
Titre  Advances in microscopic modeling of (n,$x$n$\gamma$) reactions for actinides 
Résumé  Recent developments in nuclear structure approaches offer a great mean to improve various aspects of nuclear reaction modeling and to further understand reaction mechanisms from a microscopic point of view. Recently, direct and precompound nucleon emission, for nucleon induced reaction on spherical and axially deformed nuclei, have been successfully modeled [1] using a description of target states provided by fully consistent axiallysymmetric deformed quasiparticle randomphase approximation (QRPA) calculations [2]. Direct inelastic scattering to target excitations built from onephonon QRPA states accounted simultaneously for direct inelastic scattering to discrete states, and preequilibrium emission as far as second order processes, that involve more complex excitations such as twophonon states, and multiple emission remain negligible. The QRPA nuclear structure approach has also been applied recently to determine, for a large pannel of eveneven nuclei, E1 and M1 photon strength functions [3], that play a keyrole in the modeling of statistical reactions.\\ We will review the status on the ongoing work on direct/precompound neutron emission for neutron induced reaction below 20~MeV for eveneven actinides. Target states are described as rotational bands built from each state in the target intrinsic frame, described as QRPA onephonon excitation of the intrinsic correlated ground state. QRPA excitations which display a collective character can thus be viewed as vibrational band heads. Couplings between states of the GS band and states belonging to an excited band are accounted for within a coupled channel framework. Our approach in then applied to the modeling of (n,n'$\gamma$) reactions and for both intra and interband gamma transitions [4]. For these reactions, the role played by the present microscopic approach for direct/preequilibrium emission is discussed. We finally focus on the impact on the determination of (n,n'$\gamma$) cross sections of newly calculated QRPA E1 and M1photon strength functions, that enter the description of statistical decay from compound nucleus states in the continuum.\\ [1] M. Dupuis, E. Bauge, S. Hilaire, F. Lechaftois, S. Péru, N. Pillet and C. Robin, Eur. Phys. J. A, 51 12 (2015) 168.\\[.1cm] [2] S. Péru,G. Gosselin, M. Martini, M. Dupuis, S. Hilaire, and J.C. Devaux, Phys. Rev. C 014314 (2011).\\[.1cm] [3] S. Goriely, S. Hilaire, S. Péru, M. Martini, I. Deloncle, and F. Lechaftois Phys. Rev. C 94, 044306 (2016); M. Martini, S. Péru, S. Hilaire, S. Goriely, and F. Lechaftois, Phys. Rev. C 94, 014304 (2016).\\[.1cm] [4] M. Dupuis, S. Hilaire, S. Péru, E. Bauge, M. Kerveno, P. Dessagne and G. Henning EPJ Web Conf., 146 (2017) 12002. 
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